Hemostatic clips, including aneurysm clips, are applied to blood vessels in various ways to close or strengthen a blood vessel during or after surgery. Normally, forceps are used to place or apply the clips. Forceps of the type often used are described in U.S. Pat. No. 5,104,397. Such forceps have a pair of scissors-like arms. The longer portion of the arms or handles are located on one side of the pivot and are adapted to fit into and be operated by the surgeon's hand. The arms of the forceps include a spring therebetween for biasing the gripping end of the forceps toward an open position. The forceps further include a latching device that holds the arms in different positions corresponding to the open and closed states of the hemostatic clip.
The above type of hemostat or forceps, while functioning satisfactorily, have certain characteristics which present different problems during the procedure. For example, the handle portion of the forceps are generally designed to be gripped between the thumb and forefinger and have a spread of three centimeters or more. The relatively wide spread handles of the forceps makes them difficult to rotate or turn with the fingers. Another disadvantage of that design is that the forceps have a tendency to obscure the surgeon's view of the site where the clip is to be applied. Further, the surgeon's hand first accurately positions and orients the forceps and clip with respect to the vessel. Next, the surgeon must, with a further hand motion, actuate the forceps to open and then close the clip on the vessel without changing the position or orientation of the clip. Obviously, the above is a time-consuming, delicate process which prolongs the surgery. Further, repeated operation, that is, opening and closing, of the clip applier causes muscle stress and fatigue and is very demanding of the surgeon.
To overcome the above disadvantages, a powered surgical device is disclosed in U.S. Pat. No. 5,258,007 in which two parallel arms are connected at one end to form a gripper and are operatively coupled at their opposite end to an electric motor. One arm is connected at a distal end to a movable jaw of the gripper, and its other end is connected to a nut that is threadedly engaged to a screw on the output shaft of an electric motor. Therefore, rotation of the motor will cause a translation of the nut, the movable arm, and the movable jaw. The electric motor is controlled by a pair of foot pedals, one for opening the jaw, and the other for closing the jaw. With the jaws in an open position, a hemostatic clip is placed between the jaws, and the "close" foot pedal is used to control a closing of the gripper to a first position which holds the clip in the handle. The clip can then be oriented at different angles with respect to the end of the handle. By further actuating the "close" foot pedal, the jaws are brought more closely together in order to open the clip. After the clip is positioned over the vessel, the "open" foot pedal is depressed, which opens the jaws and permits the clip to close around the vessel. While the above device addresses some of the problems presented by the more traditional forceps design, certain problems remain, and in addition, new problems are introduced.
With the electric motor in the handle of the instrument, the handle is again approximately three centimeters in diameter and relatively awkward to rotate with the fingertips. Further, the bulk of the handle is greater than the earlier scissors-type forceps, and it also has the disadvantage of potentially obstructing the visibility of the surgeon during the procedure. The electric motor extends over approximately one-third the length of the instrument and provides a significant weight at the handle end of the instrument. The heavy weight of the motor at the handle end of the instrument is not offset by the relatively small jaws at the other end of the instrument; and therefore, the instrument has a disadvantage of being unbalanced which also makes it difficult to manipulate with the fingers. In addition, the weight of the motor makes the instrument substantially heavier than the mechanical forceps it is designed to replace. The heavier weight makes it more difficult to hold steadily over time, and in longer procedures, is more demanding and tiring on the surgeon than the prior mechanical forceps.
In addition to certain disadvantages resulting from its size and weight, the electric clip applier has other disadvantages in its operation. For example, after a surgeon has carefully and accurately positioned the clip, operating the motor with a foot pedal will cause the rotor, the motor output shaft and the threaded screw to angularly accelerate. That angular acceleration will cause a slight twisting moment of the instrument, which the surgeon must overcome by bucking the torque. If that fails, the surgeon will have to reorient the clip with respect to the vessel. Further, the rotating inertia of the motor rotor, its output shaft and threaded screw results in the motor continuing to rotate through a small angle after power has been removed. That overrun causes the movable jaw to overshoot slightly from the desired position observed by the surgeon when the foot pedal was released. Consequently, in some situations, the surgeon may be required to oscillate the motor back and forth until the exact final position of the movable jaw of the gripper is achieved.
In its preferred embodiment, the electric clip applier requires the use of two foot pedals, one to open the jaws, and a second to close the jaws. It is extremely difficult for a surgeon in a standing posture to manipulate the two foot switches as implemented. It has been suggested that the device be operated by the surgeon sitting in a chair specially designed to elevate the surgeon to the desired height for the operation and having the foot pedals attached thereto. Obviously, such an arrangement severely limits the flexibility of the surgeon's motion with respect to the surgical procedure. In addition, there are other concerns and disadvantages with the use of an electric powered applier, for example, the potential problems of a power loss, intermittent power, a clutch failure, etc. The problem of a power loss is especially acute if the power loss occurs when the clip is partially applied or applied but not released. A further disadvantage is that the electric powered clip applier is substantially more costly and expensive than the manual forceps that it replaces.
Therefore there is a need for a powered clip applier that is smaller in size, lighter in weight, does not create torque on the instrument in its operation and does not require connection to hospital utilities.